Revert "linker: cleanup (removing unused VNDK_VER)"

This reverts commit 39699ea095da9ba0f7aa94ddbda459ce3138e5cc.

Reason for revert: This breaks swcodec apex. (It still uses VNDK_VER)
Bug: 140014331
Change-Id: I3a4c5b68fdd5e42fdf93c4c71f6c3be839ea8a28
diff --git a/linker/linker_config.cpp b/linker/linker_config.cpp
index a8c0e36..46c91a3 100644
--- a/linker/linker_config.cpp
+++ b/linker/linker_config.cpp
@@ -408,6 +408,9 @@
       params.push_back({ "SDK_VER", buf });
     }
 
+    static std::string vndk = Config::get_vndk_version_string('-');
+    params.push_back({ "VNDK_VER", vndk });
+
     for (auto& path : paths) {
       format_string(&path, params);
     }